Various types of locking devices have been designed for a multitude of purposes. U.S. Pat. No. 3,605,457 to Foster and U.S. Pat. No. 3,139,291 to Geresy disclose trailer hitch locking devices which are used to lock a trailer hitch tongue to the ball of a conventional type of trailer hitch. Another type of device called a coupler lock has been used for locking together the central member and outer member of telescoping type utility hitches. In this type of utility hitch, the smaller central member fits telescopically into an outer member. Apertures through both members may be aligned so that a pin may be inserted therethrough to hold the central member within the outer member. If the pin is not locked onto these members in some manner it may be removed, and the vehicle which was connected to the hitch member, such as a trailer, could be stolen.
Other types of locking devices have been designed for securing attachments and accessories to vehicles. U.S. Pat. No. 1,828,658 to Henke, Jr. discloses an anti-theft tire lock which utilizes band sections which wrap around a portion of the tire. U.S. Pat. No. 1,491,691 to Godshalk and U.S. Pat. No. 1,444,214 to Shultz disclose automobile spare tire locks utilizing a holding mechanism which presses against the tire rim to prevent removal of the spare tire from the vehicle. Spare tires for vehicles generally are mounted to racks affixed to the vehicle Since tires almost uniformly have stud holes for operably connecting the tires with studs to the vehicle, it would be desirable to use the stud holes in a tire in combination with the tire rack to lock the spare tire to the vehicle.
An improved locking device which can be used for the purposes described above is shown in U.S. Pat. No. 4,711,106 to Johnson. This device includes a stud having a threaded axial hole extending rearwardly from the forward end thereof and a keyed portion having at least one key, and a knob which locks over a forward position of the stud and includes a casing with an inner surface including at least one keyway each of which receives the corresponding key on the stud to prevent rotation of the casing with respect to the stud. The knob also includes a tumbler housing which is mounted in an axially fixed position within the casing to rotate freely when a key is inserted into the tumbler housing and to remain locked in a fixed position when the key is withdrawn.